JSD - all issues created through email randomly show as being from Jira channel or Email channel

We do not currently have the portal open for customers to login to service desk to create issues so all issues are being created from incoming emails. Some of the emails show that they are from the Jira channel, while others show that they are from the Email channel. There is no difference between the requests so I have no idea why they are being created differently. How can I ensure that all email requests come in through the Email channel?